The development of species-specific facial grimace scales for cattle, pigs, and sheep has transformed the ability to identify and treat pain in farm animal welfare.
Grimace scale development represents a revolution in farm animal pain recognition. Before validated tools existed, pain assessment relied on obvious behavioral signs that animals often suppress as prey species. Facial action units reflecting pain are harder to suppress and provide more sensitive early detection. Widespread training in grimace scale use by stockpersons and farmers would significantly improve pain detection and treatment rates.